The present application claims priority from Japanese patent application no. 2005-323082, filed on Nov. 8, 2005, the content of which is incorporated herein by reference.
The present disclosure relates to a lighting system of a vehicle such as a motor vehicle, and more particularly to an vehicle lighting system which can obtain a light distribution characteristic effective for safe driving in various driving conditions by selectively lighting a plurality of lamps.
The light distribution characteristics of a headlamp of a motor vehicle sometimes are controlled according to the driving conditions of the motor vehicle so as to secure safe driving. For example, when the vehicle is running with a dipped beam or low beam on, the light irradiated toward the right of the vehicle is shielded in order not to interfere with the vision of the driver of an oncoming vehicle. Alternatively, when running in rainy weather, the light distribution characteristics of the vehicle's headlamps are controlled to reduce the brightness in a nearest field area just in front of the vehicle so as to prevent light irradiated from the headlamps of the vehicle being reflected on the road surface and interfering with the vision of the driver of an oncoming vehicle. To implement such control, a shade incorporated in a projector-type lamp which forms a headlamp can be moved to shield or reduce the light emitted from a light source, so as to reduce the brightness in a right-forward area of the vehicle or to reduce the brightness in the nearest field area just in front of the vehicle. In other cases, an independent second shade is provided. By moving this second shade, part of the light is shielded so as to reduce the brightness in a nearest field area just in front of the vehicle.
In the foregoing techniques, part of the light emitted from the light source in the headlamp is shielded or reduced by the shade in order to reduce the brightness in the right front area or the nearest field area just in front of the vehicle. As a result, light that is so shielded or reduced is wasted, and the irradiation efficiency of the headlamp (i.e., the level of brightness in an area irradiated by the headlamp relative to electric power supplied thereto) is reduced. Therefore, it is difficult to reduce the size of the lighting system and the amount of consumed power, which reduces the fuel economy of the motor vehicle. In addition, the use of a movable shade that moves in and out of the optical path to change the irradiation area tends to be complex, which increases the production costs of the headlamp.